Microsoft has lost one of its major software engineers to perhaps its biggest rival, Google. The New York Times reports that Blaise Aguera y Arcas, who joined Microsoft in 2006 after his company Seadragon Software was acquired by the Redmond giant, will now reportedly work on machine learning projects at his new Google gig.

In a statement sent to the Times, Microsoft said, "He was a great colleague and we wish him the best in his future endeavors." In a post on his personal blog, Aguera y Arcas said that while it was "tremen­dously excit­ing" to take on a new job at Google, he also stated that leaving Microsoft was "The hard­est deci­sion of my life." He added, " It’s painful to leave behind so many won­der­ful ongo­ing projects, and even more so to leave behind such a great team."